TREASURY DEPARTMENT 

UNITED STATES PUBLIC HEALTH SERVICE 


HUGH S. GUMMING, Surgeon General 



PASTEUR—AN APPRECIATION 


AN ADDRESS 

MADE TO THE STAFF OF THE HYGIENIC LABORATORY AT THE 
CELEBRATION OF THE ONE-HUNDREDTH ANNIVERSARY 
OF THE BIRTH OF PASTEUR 

Q 143 

p 2 £5 

Copy l W. MANSFIELD CLARK 

Chief of Division of Chemistry, Hygienic Laboratory 
United States Public Health Service 


REPRINT No. 811 

FROM THE 

PUBLIC HEALTH REPORTS 

January 19,1923 
(Pages 91-98) 


A — *2- ^ I b ^ 


WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1923 























PASTEUR—AN APPRECIATION 

AN ADDRESS MADE TO THE STAFF OF THE HYGIENIC LABORATORY AT THE CELE¬ 
BRATION OF THE ONE-HUNDREDTH ANNIVERSARY OF THE BIRTH OF PASTEUR . 1 

By W. Mansfield Clark, Chief of Division of Chemistry, Hygienic Laboratory, United States Public 

Health Service. 

To-day, December 27, 1922, we commemorate the one-hundredth 
anniversary of the birth of Pasteur. 

Louis Pasteur’s mother came of a long line of plebeian aristocracy, 
if we may coin the phrase, people noted for their industry, their 
intense family loyalty, and their sensitive nature. On the father’s 
side we find a great grandfather who, born a serf, worked his way to 
the purchase of his freedom. The father, under Napoleon, fought 
his way to a Cross of the Legion of Honor, and, later, when ordered 
to surrender his sword to a policeman of the new regime, he fought 
for, and, in defiance of authority, retained the cherished blade. 

Of such stuff was Louis Pasteur—fighter, indefatigable worker, 
intellectual independent, a lover of family and friend. 

Pasteur’s son-in-law, Vallery Radot, who has given us the above 
facts, has told of the boyhood and early education of this remarkable 
man. There is little about this period that is extraordinary. There 
were times when homesickness almost got the better of a destiny 
and other times when the family purse could hardly stand the strain 
of modest educational requirements. But at last we find Louis, as a 
student in Paris, privileged to attend the public lectures of the great 
chemist, Dumas. There, in the halls of the Sorbonne, was born the 
chemist, Pasteur. 

Now, by the very nature of things, no biographer can be specific 
about the events of thought; but we have some evidence that Pasteur 
found his own problem for himself. The chum of those student days 
relates that Pasteur perceived, in the very difficulties of the existing 
crystallography, an opportunity for discovery. 

To appreciate properly the situation at that time would require 
our careful examination of the knowledge then existing. Our time 
is too short for this, and we shall have to be content with a bold 
outline. 

Let us place a book in the path of a train of electromagnetic waves, 
with the plane of the leaves parallel to the direction of propagation. 
The electromagnetic waves, vibrating in all planes perpendicular 
to the line of propagation, meet the leaves of the book. Those 
waves which are vibrating parallel to the leaves pass on. Those 
which are vibrating at an angle to the leaves of the book are damped. 
The issuing wave train now vibrates in one plane; it is polarized. 
Let us now place a second book beyond the first. The polarized 

1 Reprint from the Public Health Reports, vol. 38, No. 3, Jan. 19,1923, p. 91-98. 

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PASTEUR—AN APPRECIATION. 


waves are allowed to pass when the leaves are parallel and are shut 
off when the leaves are crossed to the plane of vibration. 

In Pasteur’s time the generalized theory was not known. But 
the principle was known in terms of light. Visible light waves are 
electromagnetic waves; so-called Nicol’s prisms of Iceland spar take 
the places of our books; and we have the polarimeter, an instrument 
used by Pasteur. 

Now, certain substances rotate the plane of polarized light. With 
such a substance absent, let the second nicol of the polarimeter be 
turned until the light is just shut off. Then introduce the substance 
between the nicols. The light from the first polarizing nicol is now 
rotated till it passes the second “analyzing” nicol. Biot had found 
that one quartz crystal may rotate the polarized light to the right, 
another to the left. Houy had found that some quartz crystals 
have a little facet inclined to the right of a plane which otherwise 
would be a plane of symmetry, while other quartz crystals have the 
facet inclined to the left. Herschel was the third investigator 
required to bring these facts together. 

Now, whereas quartz rotates when crystalized, it does not rotate 
when amorphous or in solution. On the other hand, certain organic 
compounds do not rotate as crystals, but do in solution. Here enters 
Pasteur. Anyone who has examined crystals as they are formed in 
the laboratory will realize that they seldom take the beautifully 
complete form pictured diagrammatically in textbooks. Thus, 
eminent crystallographers are excused for having missed the little 
facets on crystals of tartrates. Pasteur saw them. Now that we 
have been shown, we all have seen them. 

In the manufacture of tartrate there had been found a curious sub¬ 
stance identical in chemical composition and chemical properties 
with ordinary tartrate. It was then call paratartrate. It had 
been described as having all the physical properties of tartrate, except 
an inability to rotate polarized light. Pasteur found on the crystals, 
however, two symmetrical facets instead of the one asymmetric facet 
of tartrate. Behold the beauty of the correlation: 

Asymmetry of crystal—rotation of light by solution; 

Symmetry of crystal—no rotation of light by solution. 

Then, a disappointment. On recrystallization, the symmetrical 
paratartrate separated into asymmetrical crystals—correlation appar¬ 
ently destroyed. But here flashed genius. These new asymmetric 
crystals were of two kinds—mirror images of one another, like the 
right and the left hands. “ In spite of all that was unexpected in this 
result,” says Pasteur, “I followed, none the less, my idea. I sep¬ 
arated with care the right and left handed hemihedral crystals and 
observed separately their solutions in the polarization apparatus. 
Then, with no less surprise than joy, I saw that the right-handed ones 


4 


PASTEUR—AX APPRECIATION. 


turned to the right and the left-handed ones turned to the left the 
plane of polarization.” At last the perfect correlation: 

Symmetry of crystals—no rotation by solution; 

Right-handed asymmetry of crystals—right-handed rotation by 
solution; 

Left-handed asymmetry of crystals—left-handed rotation by 
solution. 

But Pasteur did not stop here. Since the crystals did not rotate 
while the solution did, it was evident that he must ascribe asymmetry 
to the chemical molecule. There is a left-handed molecule of tartaric 
acid. There is a right-handed molecule. There is a mixture- 
paratartaric acid, now called the racemic mixture. 

Pasteur has built up evidence for asymmetry of chemical molecules 
where before only asymmetry of crystals had been given considera¬ 
tion. 

The time was not ripe for the further elaboration of this view. 
Organic chemistry had not come into to its own, and ideas on the 
structure of organic compounds were hazy. But, 20 years later, 
when our present structural chemistry was established, Van’t Hoff, 
in Holland, and Le Bel, in France, worked out Pasteur’s ideas and 
gave us modern sterochemistry. To cite but one of many instances: 
We know to-day several sugars containing 6 carbon atoms. They all 
have identically the same composition and identically the same 
structure, except for the spatial arrangement of the atoms, the left 
and right handed arrangement of the groups about the carbon 
atoms. Theory calls for 16 steroisomers; 16 and 16 only are known. 

Pasteur’s researches upon tartrates had taken him to factories 
where he saw the destructive action of molds,. They interested him. 
He studied them; and thus was born Pasteur, the mycologist. 

Few who have felt the thrill of a discovery can escape its domi¬ 
nating influence. Pasteur was no exception. His vision of asym¬ 
metric chemical molecules made him see an asymmetric cosmos. The 
solar system can have a mirror image. Terrestrial magnetism is 
asymmetric. Life, he said, is dominated by dissymmetrical actions. 
Pasteur assailed the hopeless task of trying to influence chemical 
reactions by mechanical rotation and by magnetic fields. Accom¬ 
plishing nothing, he returned to the chemistry of life and found in 
molds the instruments which attack one steroisomer and leave the 
other. Here was room for the play of imagination. From specu¬ 
lation on the manner in which molds exercise this marvelous prefer¬ 
ential metabolism, Pasteur dragged a concrete fact of analytical 
importance: optically active plant alkaloids combine with optically 
active acids, giving salts of sufficiently different solubilities to permit 
the separation of isomers. 

An appointment to the faculty of science at Lille brought Pasteur 
to a new environment. He instructed the pupils in physics and 


PASTEUR—AN APPRECIATION. 


5 


chemistry with particular regard to the needs of local industry. 
The locality was rich in its fermentation industries, and so Pasteur, 
besides visiting iron foundries and factories of various kinds, came 
to a place where an attempt was being made to produce alcohol from 
beet juice. There was born Pasteur, the bacteriologist. 

You all know the story—his puzzling over the globules found in 
good juice and the strange forms they assume in spoiled juice; 
his examination of fermented milk, and his correlation between the 
l° n g globules in fermented milk and the long globules in spoiled beet 
juice. At last came the beginning of bacteriology—separation of 
typical fermentations; studies of pure cultures (and no mean skill 
in their chemical analysis); clear recognition of specific types of cells; 
the demonstration that fermentation is a life process. Then came 
industrial control by means of pure cultures, adjustments of tem¬ 
perature and of acidity, and the heat treatment now known as 
pasteurization. 

As “hindsight” is clearer than foresight, we can now say that 
Pasteur, the chemist, should have recognized the justice of Liebig’s 
remark, “In what respect does the explanation of fermentation 
appear clearer when you have introduced it into a living organism.” 
It was not until Buchner had separated enzymes capable of ferment¬ 
ing without the presence of living cells that Liebig and Pasteur were 
each shown in a degree to be right, but each wrong in his exclusion 
of the other’s view. 

This controversy with Liebig was more or less bound up with the 
campaign against the theory of spontaneous generation. Others 
might have been content to let the experimental facts lie in the 
archives of scientific societies and to rest smugly in the reassurances 
of savants who, with Voltaire, had ridiculed the theory of spontaneous 
generation. Not so Pasteur. Here was a superstition, a falsehood. 
To dispel the superstition, Pasteur explained. Against the false¬ 
hood, he raged. In one respect it is a pity that so much time was 
spent in hammering away at this theory of spontaneous generation, 
but in another aspect it was not time wasted. Each stroke of 
Pasteur’s hammer was a beautiful experiment; every resounding 
crash prepared the popular mind for the public-health work which 
was to follow. 

The experiments are charmingly described in “Studies on Fermen¬ 
tation.” This book is a clear and detailed account of experiments 
as they a^e done. In these days, when editors clamor for brevity 
and bookwriters must condense a world of information, it is refresh¬ 
ing to read this: “Let us boil the liquid, and, having previously 
drawn out the neck of the flask, let us close the end in the flame of a 
lamp whilst the steam is escaping, as soon as we judge that the air 
has been nearly all expelled.” 


6 


PASTEUR—AN APPRECIATION. 


In this easy manner Pasteur describes his experiments; but how 
skillfully they cut the ground from underneath an opponent, and with 
what glee Pasteur drops the opponent in the pit! A certain M. Duval 
has claimed that yeasts metamorphose to lactic ferments. Pasteur 
points out that M. Duval has made his medium alkaline with chalk 
and thus favored the lactic ferments in a mixed inoculum. Little 
points like this show that Pasteur was altogether too keen to be 
withstood. 

At one time or another I have commented upon Pasteur’s discern¬ 
ment of the effects of acidity and alkalinity on microbial life. How 
he managed it is a puzzle. It is probable that he depended upon 
color changes in litmus and thus adjusted essentially as we do to-day. 
Perhaps he made litmus work through a wider range than our dull 
eyes see to-day. Perhaps he had an awareness of intensities of 
acidity that we have recently had to define and formulate to 
appreciate. 

The absolute loyalty of the man to experimental evidence and 
his perception of significant facts are well shown in his paper entitled 
“ Animalcules infusoires vivant sans gaz oxygene.” Now, it must 
be appreciated that in Pasteur’s time oxygen was considered essential 
to all life. Some day I hope to see the list of those present at the 
French Academy when Pasteur read this paper. I am sure that in 
the list of names will be several of those who are illustrious for their 
studies in respiration and for the theory which had then become 
the dogma—no life without oxygen. Before these men, Pasteur, 
ignoring dogma, described what he saw —living cells which shun 
oxygen. 

Although the philosophical significance of this has been obscured by 
practical applications of the fact, it stirred the imagination of Pasteur. 
He made it an integral part of his theory of fermentation. He 
dwelt upon its importance in wound infections. He speculated upon 
it, and some of the speculations now forgotten are worthy of recon¬ 
sideration. 

I believe that if we examine the life of Pasteur with care and 
moderation, we shall find him to be not a giant in sheer intellectual 
power, but rather an exceptionally keen observer, possessed of quali¬ 
ties often attributed to genius—the mind constantly prepared to 
receive the significant impression, infinite patience to follow it, and 
power to visualize the consequences. Many of the facts which 
Pasteur is commonly believed to have discovered had been observed 
before. .But the observations were islands. Pasteur was the earth¬ 
quake that lifted the islands to a continent. 

All this work on fermentation was causing a “fermentation” in 
men’s minds, and gradually (no one can tell exactly how) there 
effervesced the misty idea that the contagious diseases of man and 
animals are somehow akin to the contagious “diseases” of beer and 


PASTEUR—AN APPRECIATION. 


7 


wine. At any rate, we at last find Pasteur’s old friend Dumas urging 
him to assail the problem of silk-worm disease. Duclaux states that 
Pasteur s only training for this work was witnessing the dissection of 
a May beetle larva. But once in the field, Pasteur fell back upon his 
trusted method—personal test of every idea by experimentation. 
Thus was born Pasteur, the pathologist. 

Six strenuous years gave France the brilliant results that saved her 
silk industry. Then, after a return to older problems, came the last 
period of Pasteur’s rich life. You who are pathologists know the 
story better than I—the work on chicken cholera, the chance discovery 
of attenuated virus, and the genius that snatched from an apparent 
failure the light that illuminated Jenner’s principle of vaccination; 
the work on anthrax, and the dramatic public experiment on anthrax 
vaccination; septicemia, and the attack upon the unhygienic methods 
of the lying-in hospitals; the inspiration given to Lister; and at last the 
eventful day when courage was summoned by this layman in medicine 
to treat a human patient, little Joseph Meister, the victim of a rabid 
dog. 

It is chiefly for the work of these later years that Pasteur is being 
honored the world around to-day. And the reason is clear. When 
history is written as it will some day be written, the years of man’s 
political rise will seem a dreary waste of wars and quarrels, and the 
tinseled glories of sordid kings. Real history begins when man began 
to conquer his environment. Among the conquerors, Pasteur was 
preeminent. 

But when this story is told, when public health work has done its 
task and we are secure against our microscopic enemies, there will still 
be another story—that of man’s attempt to understand the methods 
he has turned to practical uses. Here, too, Pasteur will be honored. 
Let us judge him by what he has done and what we have left undone. 

He revealed the asymmetry of chemical structure and the asym¬ 
metric preferences of fermentation. The chemist uses the fact to 
separate isomers; the bacteriologist uses the fact to distinguish species. 
We now picture chemical structures better, but we have not explained 
the asymmetry of life processes. 

He set straight the sequence of events in fermentation. We use 
the knowledge and have added details, but we do not really under¬ 
stand the fundamental chemistry of the simplest phase of fermenta¬ 
tion, or the nature of virulence. 

He rediscovered and added significance to anaerobiosis. The 
bacteriologist uses the fact for the cultivation of pathogens, and the 
physiologist forgets the fact and still says all life is dependent upon 
oxygen. Almost every known method for obtaining anaerobiosis 
washed in principle by Pasteur and his pupils. Yet every volume 
of the several bacteriological journals contains a so-called new 


8 


PASTEUlc—AN APPRECIATION. 


method, adding little but a mechanical “ stunt” where we find Pasteur 
seeking a principle. 

In short, Pasteur touched upon, and, at each touch illuminated, 
great problems which I may call problems of understanding as con¬ 
trasted with problems of practical ways and means. Because the 
practical ways and means were questions of life and death, Pasteur, 
the humanitarian, threw his great energy into their solution, and 
with such success that he is revered among the ignorant as a sort of 
miracle man. Let us remember, however, that the practical ways 
and means were tribute moneys levied by Pasteur, the humanitarian, 
upon Pasteur, the scientist. Here was an insatiable craving to 
understand—the projection of hypotheses into the unknown, mis¬ 
takes, failures, disappointments, pragmatic results which satisfy the 
utilitarian mind—and, at last, illumination which widened the 
horizon and brought honors, but left Pasteur still a pioneer, lonely, 
on a new far-flung frontier. We think our horizon widened since 
Pasteur’s time. In reality we have to do not with the horizon of the 
trigonometer but with the horizon of the pioneer. We have gone 
around great areas difficult of exploration. From their darkness stalk 
untamed things which haunt us; and, confessing our impotence, we 
start anew from—Pasteur. 

As Korzybski has emphasized, the distinctive attribute of man is 
his ability to propagate the labor of those who have passed. In this 
way man has attained a new dimension. He can “ bind time.” He 
makes the past the intellectual present and the future the present 
vision. Thus it is that, in a sense rigidly logical and beautifully true, 
we have Pasteur with us to-day. He points to the facet on the 
crystal of tartaric acid; we would not see it otherwise. He gives us 
rabies prophylaxis. Our hands administer. Our minds have added 
little. He emphasizes the fact of anaerobiosis and, recalling his own 
efforts to understand, he asks if we see the relation between anaerobic 
fermentation and the recently discovered anaerobic phase of muscle 
metabolism. 

We have led his bacterial friends to beneficent uses. We have 
encircled the world in a relentless campaign against his microbial 
enemies. Pasteur’s eyes sparkle—then flash. Ever a man of vigor, 
he brings down his fist—“we foresee the accomplishment of this 
humanitarian task, but when, oh when, shall we understand the 
chemistry of immunity?” 

Pasteur—crystallographer, chemist, mycologist, bacteriologist, 
pathologist. The terms are too many. Let us name him investi¬ 
gator, and, like him, mingle our chemistry and bacteriology. 

Pasteur—investigator, benefactor. He lives with us. His great 
heart, the heart of a living friend; his genius our inspiration. 

o 


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